Buffer overflow in Asuswrt-Merlin

CVE-2018-5721

Stack-based buffer overflow in the ej_update_variables function in router/httpd/web.c on ASUS routers (when using software from https://github.com/RMerl/asuswrt-merlin) allows web authenticated attackers to execute code via a request that updates a setting. In ej_update_variables, the length of the variable action_script is not checked, as long as it includes a "_wan_if" substring.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.019 (79.3th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2018-5721: held from 0.019 to 0.019.

EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2018-5721?
CVE-2018-5721 is a high-severity vulnerability in Asuswrt-Merlin, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2018-01-17.
How severe is CVE-2018-5721?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2018-5721 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.